1. Field of the Invention
The present invention relates to the manufacturing method and device for an electret processed product, and in particular relates to the manufacturing method and device for an electret processed product enabling a high quality electret processed product to be produced at a low cost.
2. Detailed Description of the Prior Art
Conventionally, an electret processed fiber sheet has been used as an air filter material having an excellent performance with a low pressure loss. As manufacturing methods for the electret processed fiber sheet, a method for electret processing by means of corona discharge generated by applying a high voltage to a fiber sheet including a synthetic fiber nonwoven fabric and the like (refer to Japanese Patent Laid-Open No. 1986-102476 and so on), and a method for also electret processing by means of the same corona discharge generated by applying a high voltage using wire electrodes to a film sheet, thereby making the film sheet into a nonwoven fabric (refer to Japanese Patent Laid-Open No. 1982-14467 and so on) are known.
However, since the method for electret processing by means of corona discharge is performed by means of corona discharge generated by applying a high voltage from a needle shape or wire electrode to the surface thereof, by placing on an earth electrode or while running it, unevenness tends to occur due to the distance accuracy and the like between a high voltage applying electrode and the earth electrode, thereby resulting in problems like uneven charging of the electret processed sheet and damage of the sheet due to spark discharge.
Further, there has also been a problem of high costs because high voltage units are generally priced high and expenses are required for the safe operation and maintenance thereof.